1. Technical Field
The present invention relates to a chip bonding method and a driving chip of display, and more particular to a driving chip in which the bonding stability thereof is improved and a chip bonding method in which the bonding stability between a display panel and a driving chip of the method is improved.
2. Related Art
Accompanying the development of display technologies, display devices are wildly used in commercial electronic device or computer device; liquid-crystal display and organic light emitting diode display (OLED display) technologies, are flourishing in particular. In order to make products thin and light, the chip on glass (COG) technique is applied to manufacturing the liquid-crystal display, thus reducing significantly the thickness of the liquid-crystal display. The chip on glass technique is described thus: after the driving chip is aligned with the contact pads on the glass substrate, a hot pressing procedure is applied to allow the driving chip to bond to the glass substrate via an anisotropic conductive film (ACF) so as to reduce the circuit board which is necessary in the traditional tape carrier package procedure. Consequently, the thickness and the weight of the display can be reduced, and the cost for manufacturing the display may also be reduced.
Since the display resolution requirements have become more and more important, and the display manufacturers tend to reduce costs as much as possible, the number of the driving chips for a single display must be reduced to achieve display cost reduction, thus increasing the number of bumps on a single driving chip.
Conventionally, in the driving chip package procedure (for example, in the COG procedure), the forcing center of the pressing head of the pressing fixture is aligned to the center of the driving chip to undergo the hot pressing operation, thereby allowing the bonding between the driving chip and the display panel via the anisotropic conductive film. However, in the following quality control procedures, it is realized that when the number of the bumps on the driving chip increases, the conductive particle indentations of the anisotropic conductive film will not be uniform; particularly, the indentations of the output side of the driving chip will be lighter than those of the input side of the driving chip (generally, the number of the bumps disposed at the output side of the driving chip is more than that of the bumps disposed at the input side of the driving chip). Consequently, the bonding stability between the bumps of the driving chip and the glass substrate is worse, thereby reducing the overall defect-free rate of the products and affecting the quality of the product.